Revert "netfilter: handle the connecting collision properly in nf_conntrack_proto_sctp"

This reverts commit 0ba93485 which is
commit 8e56b063 uptream.

It breaks the Android ABI so revert it for now, if it is needed in the
future, it can be brought back in an ABI-safe way.

Bug: 161946584
Change-Id: Ia03ea49365e6ce063194738b22f77d2a403ea3a4
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>